92 Lumina-Sticky brakes

Hello all! Need some help! I've been working on a 92 Lumina van with ABS and am trying to figure out why the front drivers side brakes are sticking. They won't release. I have personally just replaced the pads, rotor, and caliper to no avail. What else is there? I was thinking the master cylinder or ABS unit that's attached to the master cylinder may be bad. I'm stumped. Any ideas are appreciated! :)

Thanks!
Eric

Check the brake hoses..I have had some that will allow pressure towards the caliper, but will not release the pressure towards the master cylinder..cut one open and found a flap of rubber acting as a one way valve.

Come to think of it, while I was changing out the caliper and such, I did notice that the brake line that goes to the caliper was bad. Bad, as in not leaking, but the outer rubber part where it bends was showing the inner threaded hose. Hmmm. I'll change that out and see what happens.

Thanks! I'll keep you all posted.